The present invention generally relates to an electromagnetic tracking system. In particular, the present invention relates to an improved system and method for detecting errors in the electromagnetic tracking system.
Many medical procedures involve a medical instrument, such as a drill, a catheter, scalpel, scope, shunt or other tool. In some cases, a medical imaging or video system may be used to provide positioning information for the instrument. However, medical practitioners often do not have the use of medical imaging systems when performing medical procedures. The use of medical imaging systems for instrument tracking may be limited for health and safety reasons (e.g., radiation dosage concerns), financial limitations, physical space restrictions, and other concerns, for example.
Medical practitioners, such as doctors, surgeons, and other medical professionals, often rely upon technology when performing a medical procedure, such as image-guided surgery or examination. A tracking system may provide positioning information for the medical instrument with respect to the patient or a reference coordinate system, for example. A medical practitioner may refer to the tracking system to ascertain the position of the medical instrument when the instrument is not within the practitioner's line of sight. A tracking system may also aid in pre-surgical planning.
The tracking or navigation system allows the medical practitioner to visualize the patient's anatomy and track the position and orientation of the instrument. The medical practitioner may use the tracking system to determine when the instrument is positioned in a desired location. The medical practitioner may locate and operate on a desired or injured area while avoiding other structures. Increased precision in locating medical instruments within a patient may provide for a less invasive medical procedure by facilitating improved control over smaller instruments having less impact on the patient. Improved control and precision with smaller, more refined instruments may also reduce risks associated with more invasive procedures such as open surgery.
While various tracking systems and methods have been developed for monitoring the position of medical instruments with respect to a patent's anatomy, current systems and methods are not perfectly accurate for all clinical applications. For example, optical tracking systems are sensitive to objects, e.g. draping, blood, contamination, obstructing the view of the optical reflectors. Electromagnetic (EM) tracking systems generally do not have line of sight problems. The presence of metallic or ferromagnetic objects nearby the EM transmitters (Tx) or receivers (Rx), however, may distort the transmitting EM fields. Such a distortion may result in inaccurate tracker position and orientation (P&O) measurements. To mitigate the risk, such navigation systems usually have an error detection mechanism to monitor the quality of the tracker P&O updates and report warning messages to the system and/or user to disable the navigation assistance if a malfunction is detected.
Current error detection mechanisms for detecting EM distortion, however, may have high rates of false occurrences. For example, current error detection systems and methods may indicate the presence of an error in the EM tracking system when, in actuality, no error is present. A high rate of false occurrences may be disruptive to the user. For instance, a high rate of false occurrences may be disruptive during surgery or other medical procedure. Also, a high rate of false occurrences may undermine the accurateness of the tracking system in the mind of the user in such a way that the user may not trust the tracking system. Accordingly, a surgical procedure may be more invasive than necessary.
Thus, a need exists for a surgical navigation system and method that allows for surgical or other medical procedures to be performed in a more reliable and less invasive manner. A tracking system and method that operates with a more accurate error detection system and method would be highly desirable. Such a system and method may be easily adjustable and configurable. Such a system and method may provide a more accurate detection of EM distortion, and thus a more accurate detection of system errors.